Bicycle hub dynamo



Dec. 26, 1950 A. RABL 2,535,453

BICYCLE HUB DYNAMO Filed May 11, 1949 2 Sheets-Sheet l fr v "n:

E92 y 1 3311343m2116 Blwcuor mmm @A51 Ctorneg Dec. 26, 1950 Flled May 11, 1949 Patented Dec. 26,1956

" UNITED STATES PATENT OFFICE BICYCLE HUB DYNAMO Alfred Rabl, Vienna, Austria Application May 11, 1949, Serial No. 92,539 In Austria May 13, 1948 This invention relates to a bicycle hub dynamo in which the dynamo armature and the driving member are connected by means of a transmission gearing which can be coupled with the bicycle, if required, by means of a switching member and which is adapted to drive the dynamo at an increased speed. The known transmission gearings comprising toothed wheels are not ehicient enough and owing to their transmission ratios do not give enough light as required in modern tramo conditions. Neither do bicycle dynamos driven by frictional gearings give a satisfactory output of light, the speed of rotation of the dynamo being too small, especially at low driving speed.

' It has been proposed'already to improve the output of bicycle hub dynamos by connecting several ge-aring stages, consisting of axial pressure ball bearings so as to form a transmission gearing, which comprises a single means for applying pressure to all gearing stages and which transmits the rotation of the wheel hub to the dynamo rotor according to the transmission ratio. In known gearing, the rotating and revolving gearing members of all gear stages are accommodated in-a casing, which also contains the pressure means, which abuts on the one hand on the casing, on the other hand on the gear members. This method of applying pressure is unsuitable because it is dependent on the casing which encloses the gearing, thus co-utilizing the wheel hub as a gearing member.

This invention is based on the idea of combining the gear members with the pressure means in a unit which enables a positive transmission of forces, so that the whole transmission gearing, together with the dynamo, can be built into and out of the wheel hub in a simple manner and, moreover, utmost eiiiciency is achieved as regards torque transmission.

. Whereas transmission gearings are known in which pressure is positively transmitted similarly as by axial pressure ball bearings, those gearings have a single gear stage only, whose split inner and outer races are subjected to the axial pressure of a spring for providing the frictional pressure required for transmitting the torque.

In oontradistinction thereto the problem at hand is solved according to the invention in that the races and the revolving balls of at least one pair of the gear stages of a multi-stage gearing are subjected to pressure in mutually opposite axial directions by a pressure means, and that both said gear stages are held together in two directions opposite to the pressure exercised vby 13 Claims. (Cl. 171-209) said pressure means by an axial thrust bearing common to both said stages, all gear parts of both said gear stages together with the pressure means and the axial thrust bearing thus forming an integral system which is adapted to effect a posi. tive transmission of pressure.

This solution for the first time enables the reduction of a dynamo together with the trans-v mission gearing to a. unit of the smallest possible size which can be conveniently built into and out of a, normal size wheel hub. Moreover, the new design of the gearing results in a high transmission ratio and thus also in a very high light output of the dynamo.

rEhe means for applying pressure to the gear stages may be developed in many variations, some of which may be mentioned hereafter. The pres sure means may consist, e. g., of an elastic tension means, which attacks on the one hand at the input end of the gearing, on the other hand at the races revolving at the output end of the gearing, and which holds together the gear members by axial pressure so as to form an integral system. It is also possible, however, to use the dynamo itself as a pressure means and to utilize the attraction of the stator, which is provided with a winding, for generating the frictional pressure required `for the transmission.- Itis also possible to subject the pressure means to centrifugal force. In multistage transmission gearings one portion of the gear, e. g., the input stages, may be subjected to the influence of an elastic pressure means and the other gear stages to that of the dynamo magnet.

The invention provides a gear which is particularly suitable for being built into-the wheel hub when the positive transmission of pressure between the gear members, which are subject to the pressure exercised by said pressiue means, is alforded by the bearing cone fixed to the wheel axle and holding the whole gearing, which together with the wheel hub is secured against axial displacement but freely rotatable on the wheel axle.

The drawings show, by way of example, several embodiments of a hub dynamo according to the invention, in sectional elevations.

Fig. 1, relating to the first embodiment, shows a three-stage transmission gearing having an elastic pressure means.

Fig. 2 a variation of the design shown in Fig. 1.

Fig. 3 shows a transmission gearing having a pressure means which is subjected to centrifugal force.

Fig. 4 shows an embodiment 1n which the gearing is combined with an elastic and a magnetic preessure means.

Fig. I5 illustrates a transmission gearing having two bearing supports provided on a bearing cone.

Figs. 6 and 7 show two designs for damping the wheel impact on the gearing.

The rst embodiment of the bicycle hub dynamo is mounted in the hub casing I of the front wheel and consists of the dynamo proper and the transmission gearing. In this case the gearing comprises three speed stages. The gear stages II and III, which are combined in a system that is adapted to eiect a positive transmission of forces, have outer races 2 and 3 and inner races 4 and 5, respectively, which races present their tracks to the two ball trains Gand '1. A spring ring 8 or a pressure element made from rubber is provided between the outer racesv 2 and 3 and applies elastic pressure, in mutually opposite axial directions, upon the outer racesy2 and 3. Said v,outer races 2, 3 transmit this pressure through the two ball trains 6 and I to the inner races 4. and 5. The inner races 4, 5., are freely and rotatably supported in axial opposition relative to each other by means of an axial thrust ball bear-ing 9, which absorbs the pressure forces acting in mutually opposite directions and thus provides a positive transmission of forces so that the gearing rotates free from axial pressure.

The inner race of the gear stage II is integral with the ball cage I of the gear stage III. Similarly the inner race 5 of the gear stage III is directly connected with the rotor II of the dynamo, the attractive force of the dynamo magnet thus being permanently utilized as an additional pressure force acting on the gear members or" the gear stages II and III. The balll cage I2 of the gear stage II is made with the inner race I3 of the gear'stage I in one piece, which also has a ball race for the axial ball bearing I4, whose inner race is developed as a nut threadable on the X-ed axle pin I6 which forms the wheel axle. The V outer race 2 of the gear stage II is integral with the outer race of the gear stage I. The outer race 2 is tted into the wheel hub and is thus carried along when the latter rotates. The outer race 3 of the last gear stage, being displaceably fitted axially intov the wheel hub I,-is car-riedalong with the rotatable outer race 2 'by means of the spring ring 8. The outer race 3 is so held in the wheel hub I on the one hand by the friction of its fit, on the other by the pressure of the spring 8, that during the transmission of a normal torque it remains undisplaceable rel-ative to the wheel hub I and the outer race 2, whereas when the gearing is overloaded, e. g. by reason of gear parts being jammed or as a result ofexcessive driving power, the outer race 3 is carried along by the ball train "I rotates relative to the Wheel hub I. The outer race 3 thus serves as a protection means against the blow-ing out of the bulb owing to excessive voltage and against accidents caused by gearing defects. v

' Whereas the Wheel -hub I is, together with the transmission gearing, freely rotatably mounted on the xed wheel axle I6, on the one sideby means of the ball bearing I4, the wheel hub is rotatably mounted and secured against axial displacement on the other bearing'side by means of the ball bearing I1. In this specific case, said bearing I'I is developed as a current collector. For this purpose the inner race I8 of thev ball bearing I'I is mounted on a sleeve I9Vof electrically insulating material fitted to the xed wheel axle IE, and is thus electrically insulated against the axle and may be firmly connected, as a current collector, with the light cable (not shown) in any suitable manner. The outer race 2D of the ball bearing I'I also has a strip 2I of electrically insulating material around its periphery, by which it is electrically insulated against the dynamo magnet comprising the winding 22. The -wire end 2t of the winding 22, therefore, may be directly connected with the outer race 20, the need for any complicated means for collecting the current thus being eliminated.

The cage ring 25 of the gearing stage I is utilized for switching the hub dynamo in and out. Said cage ring is mounted so as to be freely rotatable and lcan be locked to the wheel axle I6 by means of a switching or control lever 2S. For this purpose, the cage ring 25 is provided with radial recesses 2'! arranged in a circle. The lever 28 is mounted by means of a pivot pin 28 in the eye 29 `of a bearing arm 3Q which is xed to the wheel axle, the lever being adapted to pivot within such limits that its short locking arm 3l may be thrown into or out of the recesses 2l of the cage ring 25. When thrown out, the cage ring is disengaged from the switching means or lever 3|, 2t and rotates freely and Iwithout resistance, the gearing thus being inoperative.

For switching in the hub dynamo, the switch, ing means 26 is thrown into one of the recesses 21 of the cage ring 25, which is thus xed vrelative to the wheel axle I5. The balls .of the gear stage I thus revolve on the outer race 2 and drive the inner race I3 at an increased speed. This increased speed is transmitted Iby the inner race It to the ball train 6 of the gear stage II, said ball train 6 being subjected to the frictional pres-.-I sure of the spring ring 8 and to the attractive force of the dynamo magnet and driving the in ner race 4 of the gear stage II at a speed which is increased according to the transmission ratio. The transmission of the torque from the gear stage II to the gear stage III is eiected by the inner race 4 through the ball cage I0, by which thevballs l, just as in the previous gear stages I and II, are caused to revolve in the same sense of rotation. The ball train I transmits its rotation at an increased speed to the inner race 5 and thus to the rotor I I of the dynamo.

' The transmission ratios of said three gear stages are so chosen that the dynamo rotor has, even at low driving speed, a speed of rotation which en- Suresv an electric power output suiilcient for giving good light. The gearing members are so formed that their manufacture as well as their assemblyand removal may be carried out in the simplest possible manner.

' I n the second embodiment as shown in Fig. 2, the elastic element is a spring ring 8 arranged be'- hind the outer race 3.. For this reason, the Guter race 2 of the gear'stage II is provided with a sleeve 2a which surrounds and extends beyond the opposite side of the cuter race 3, said sleeve ter minating in an inturned annular flange against which the spring ring 8 bears. 8 thus tends tc elastically press the two outer races 2 and 3 together and to press the ball trains E and 'I against the inner races 5 and 5. The inner races'li. and 5 are supported in opposition to each other through the Vaxial thrust ball bear-- ing 9 so that a positive transmission of forces is achieved over the gearing' members ofthe gear stages II and III. vThe gearing is switched in and' out in the manner described heretofore by locking Said spring ring mission gearing.

the cage ring by means of the switching means or lever 26.

The embodiment shown in Fig. 3 is an example of a transmission gearing having a pressure means which is subjected to centrifugal force. In this case the pressure means consists of ngers 32 or their equivalents, which bear on the one side against the inner race 5 of the last stage III and onv the other against an annular fiange 33 of the sleeve Ila connected with the dynamo rotor Il, and are subjected tothe influence of lever arms having adjustable centrifugal weights 34 for generating the pressure required. The pressure exercised by the pressure means 32 is on the one hand transmitted through the ball train I of the stage III to the outer race 2, and from the latter through the ball train 6 to the inner race 4, and is on the other hand absorbed by the bearing sleeve Ila of the dynamo rotor and transmitted to the axial thrust ball bearing 5l, which eects the positive transmission of forces. The pressure exercised on the gearing is thus regulated in accordance with the speed of rotation ofthe driving part. The outer races may also be provided with ngers 32 in the same manner.

Fig. 4 shows another embodiment of the trans- In this case, the three gear stages I, II, and III are subjected to the influence of an elastic pressure means and of a magnet. In this specific case the gear stages I and II are subjected, as in Fig. l, to the influence oi an axially elastic ring 3, whereas the gear stage III consists of an outer race 3 connected with the magnet 23, and of an inner race 5 connected with the dynamo armature Il, the ball train 'l revolving between said races 3 and 5 and being subjected to the attractive force between the two dynamo parts il and 23. The dynamo armature Il is mounted in the magnet 23 so as to be freely rotatable in the wheel hub by means of a bearing 35. A slip ring for the armature H is provided by a contact spring 36 which is connected to the armatureby a lead 3'! and bears against the inner race I8. The contact spring 36 conducts the current to the ball bearing, to whose iixed inner race I8 the lamp lead may be connected. This design is distinguished by its great simplicity and in that the gearing parts form a system in which a complete positive transmission of forces is ensured.

The embodiment shown in Fig. 5 illustrates a special manner of mounting the wheel hub and the gearing on a conical sleeve. For this purpose the outer race and the inner race of the first gear stage are similar to the outer race and inner race of the second gear stage. The pressure means, consisting of a spring ring 8, is inserted between the two cuter races of the gear stages I and II, the pressure exercised by said ring being evenly transmitted in both directions through the outer races to the ball trains of the gear stages I and II. Said ball trains bear against the inner races of the two gear stages, which inner races are also made equal to each other and bear in mutually opposite directions against a common bearing cone il on which they are `freely rotatable. In this case the pressure exercised by the spring ring 8 is absorbed through the two axial thrust ball bearings 9 and Il by the bearing cone 4| so that a positive transmission of forces through all gear parts of the two gear stages I and II is eiected. At the same time the wheel hub l, which is tted to the outer race of the rst gear stage, is supported on the wheel axle I6 in two bearing points by means of the two axial thrust ball bearings 9 and l1 in such a manner that the hub can be xed to the wheel axle by means of a single bearing cone, the previous need for an adjustment of the hub in respect of the wheel fork being eliminated. This design has not only the advantage of aifording aparticularly convenient method of assembly, but also enables the elastic pressure means to partially or completely compensate any impacts which may act upon the gearing. In this embodiment of the transmission gear the gearing stage III is developed as in the embodiment shown in Fig. 4, the gearing parts of the gear stage III being pressed against each other by the armature and the magnet of the dynamo.

It may be mentioned that the principle on which this gearing is designed is in no way limited as regards the number of gearing stages.

In order to prevent the transmission of impacts of circumferential direction from the wheel to the transmission gearing, the lockable cage ring 25 may, as shown in Fig. 6, hold the balls by means of elastically exible tongues 38 or the ring may be held, as shown in Fig. 7, by means of a control lever 2G which is to some extent elastically exible in the direction of its switching movement. Owing' to the flexibility provided in the direction in which the balls rotate, both designs aflord a certain play by which any impacts coming from the wheel are compensated.

What I claim is:

1. A bicycle hub dynamo provided with a multistage transmission gearing consisting of axial thrust ball bearings arranged between the dynamo armature and the driving part, and adapted to be selectively thrown in and out, comprising: pressure means for exercising axial pressure in opposite directions upon the races and balls of two adjacent gear stages, and an axial thrust bearing for holding said two gear stages together against the pressure exercised upon them by said pressure means.

2. A bicycle hub dynamo as set forth in claim 1, in which said pressure means consist of an electic eement inserted between two races of two adjacent gear stages and in which the other two races of said gear stages are axially undisplaceably connected.

3. A bicycle hub dynamo as set forth in claim l, having a stator provided with a winding, and a magnetic rotor, said stator and rotor being connected each with a ball race of at least one gear stage and holding together the gear parts revolving between said races.

4. A bicycle hub dynamo as set forth in claim 1, comprising centrifugal weights for varying the axial pressure exercised by said pressure means.

5. A bicycle hub dynamo as set forth in claim 1, in which one of the outer races subjected to the pressure of said pressure means is a frictional fit in the wheel hub and adapted to remain in its position relative to the hub during the transmission of a normal torque and to rotate relative to the hub when the torque to be transmitted is excessive.

6. A bicycle hub dynamo as set forth in claim 1, comprising a single bearing cone for holding together the gear stages subjected to the pressure of said pressure means, said cone being adapted to support the whole system comprising the gearing and the wheel hub freely rotatable on the wheel axle, said system being secured against axial displacement.

7. A bicycle hub dynamo as set forth in claim 11;. comprising an axial thrust ball bearing for eaclr or the gear stages. and subjected tov the. pres.-v su-reof said pressure; means, a single bearing conev for: said. twogear stages, said gear stages'r being supported and thrust in opposite' axialdirections against said'. bearing. cone" throughv said axial thrust ball. bearings.

8. A bicycle huls` dynamo as set' forth inv claim 12,.: in which the leali cage ol" said preliminary gearsta'ge has recesses arranged in a circle', and which comprises a switching means fixed tov the Wheel axle: and selectively insertahle into said recesses` for locking said., cage against rotation.

9. A bicyclehuh dynamo as set forth inv claim 12;. comprising elastically flexible tongues attached to the ball cage of said preliminary gear stage, Said tongues being in engagement with the halls of. said preliminary gear stage.

l0. A bicycle hub dynamo as set forth. in claim l2', comprising a somewhat resilient bolt for looking'the `hall cage of said preliminary gear stage against roation'K 11. ./i bicycle hun dynamo provided with a multi-stagev transmission gearing consisting; of

axial thrust ball hearings` arrangedv between the dynamo arma"' the driving part and adapted' to be seieetivelyV thrown in andi out, cornprlsing pressure means for exercising axial pressure. in opposite direcli'ons the' races and balls of' twoadja'cent. gear stages', an axial thrust bearing for holding said two gear stages together against the pressure exercised upon them by said pressure means: a stator provided with a winding, a magnetic rotor, said stator and rotor being connected each with a hallI race ofV at least one gear stage and holding together the gear` parts revolving between saidrraces, and a separate rotor bearing arranged inside the stator.

` 12. A bicycle hub dynamo provided with a multi-stage transmission gearing consisting of axial thrust ball hearings arranged. between theV dynamo armature and the driving part, and adapted to' be selectively thrown in and out, comprising' presw surel means for exercising' axial pressure in oppo site.'y directions: upon the'. races; and balls of two adjacent gear stages, an axial thrust. hearing for' holding. said, two, gear stagesV together against the pressure exercised upon` them'. loyA said. pressurev means a gear stage preliminary to the two gear stages subjected. toK the pressure of said pressure means,V said preliminary gear stage having an outer.v race fitted in the wheel hub` and an inner race' formed. asa ball cageffor engaging with thev balls of. the: gearstage adjacent to said. preliminary stage, a ballI cage for the bal] train of said preliminary stage', and means forv locking said latterA ball. cage against rotation.

1-3.: loicyclet` hub dynamo provided with. a multi-stage transmissionr gearing consisting of axialtthrust ball bearings arranged between the dynamo armature and the driving part, and adapted to beiselecti-vely thrown inland out, comprising pressure means for exercising. axial pres"-r sure in` opposite directions` upon the races and balls of two-adjacent gear. stages, an axial thrust bearing for'holding said two gear stages together against the pressure exercised upon them by said pressure means, a stator provided with a winding, a magnetic rotorsaid stator and rotor bein-g connected each With a ball race of atr least one gear stageand holding together the gearing parts revolving between. said races, an electrically insulated.v axial thrust ball bearing supporting the dynamo sta-tor and. the Wheel hub, said bearing comprising an inner racel iixedY to the wheel axleand developed as a current collector, and an outer race connected With the wire end of the armature winding.

ALFRED RABI...

REFERENCES CITED Dalen Nov. 23, 1937 Rabl June 29, 1943 Number 

